I'm no poultry psychiatrist but I think they show some type of "emotional" response. I can hear differences in the noises that tell me the run is A-OK, or there is a challenge to the pecking order, or when one gets outside of the pen where she is not supposed to be. And then there is the predator alert panic call.
They also show contentment/happiness when I go into the pen or coop. They run over and squat for the rump rub, treats and will make a cooing/purring noise. Even my shy bantams are interested in that and will wait for their turn but only allow the rump rub for a few seconds.
As for being upset over new things, I just don't see it. Probably because since they were peepers, I have moved them around from brooder to brooder, from inside to the garage. From the garage to outside and back in at night before I had the coop finished. Plus I have portable fencing so I move the run on a regular basis to keep the grass growing and give them new areas to scratch in. They follow me and get under foot whenever I start working in the pen, coop or yard.
I think the early conditioning set the tone for their behaviour.